This turn down the heat why a 4°C warmer world must be avoided provides a snapshot of recent scientific literature and new analyses of likely impacts and risks that would be associated with a 4°C warming within this century. It is a rigorous attempt to... 更多显示This turn down the heat why a 4°C warmer world must be avoided provides a snapshot of recent scientific literature and new analyses of likely impacts and risks that would be associated with a 4°C warming within this century. It is a rigorous attempt to outline a range of risks, focusing on developing countries and especially the poor. A 4°C world will be one of unprecedented heat waves, severe drought, and major floods in many regions, with serious impacts on ecosystems and associated services. But with action, a 4°C world can be avoided and we can likely hold warming below 2°C . This report spells out what the world will be like if it warmed by 4°C , which is what scientists are nearly unanimously predicting by the end of the century, without serious policy changes. The 4°C scenarios are devastating: the inundation of coastal cities; increasing risks for food production potentially leading to higher malnutrition rates; many dry regions becoming dryer, wet regions wetter; unprecedented heat waves in many regions, especially in the tropics; substantially exacerbated water scarcity in many regions; increased frequency of high-intensity tropical cyclones; and irreversible loss of biodiversity, including coral reef systems.
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